European, thin, supplying wood (5)
I believe the answer is:
ebony
'wood' is the definition.
(I know that ebony is a type of wood)
'european thin' is the wordplay.
'european' becomes 'E' (abbreviation e.g. EU).
'thin' becomes 'bony' (similar in meaning).
'e'+'bony'='EBONY'
'supplying' is the link.
(Other definitions for ebony that I've seen before include "Black hardwood" , "Very dark brown" , "Tree with blackish wood" , "Hard block tropical wood" , "'Hard, dark wood (5)'" .)